For the third time this year, Sydney has been hit by major floods. Scientists blame intense rainfall on a combination of factors – but, on social media, unfounded allegations of “weather manipulation” have spread widely.
About as much as eight months’ worth of rain has come down in just four days, bringing parts of Australia’s largest city to a standstill.
Experts say no single factor can explain this extreme weather, pointing instead to warmer oceans and saturated soils as contributing factors.
But conspiracy theorists aren’t buying it. On social media, they blame the extreme rainfall on “cloud seeding” and “weather manipulation”.
There is no evidence to back up such theories, but this hasn’t prevented falsehoods from reaching thousands of people online.
What is cloud seeding?
Cloud seeding is a real thing. It involves manipulating existing clouds so that they produce more rain or snow.
This is done by firing small particles (usually silver iodide) into clouds. Water vapor gathers around the particles and eventually falls as precipitation.
The technique has been around for decades. It’s been used all around the world to – for example – help irrigate crops.
But there is no evidence to suggest cloud seeding has anything to do with the current rainfall in Sydney. That hasn’t stopped some TikTok users from denouncing “weather engineering”.
They say it’s all part of a government plan to “weaponise” the weather against its own people – a popular conspiracy trope that has been around for years.
“The idea that this is happening on a widespread scale, and that there is some motivation to manipulate the weather is a complete myth,” says Dr Ellie Gilbert, a climate scientist at the British Antarctic Survey.
And yet, this myth seems to have found an audience. Many of the accounts seen by the BBC posting this type of content have also shared other conspiracy theories involving global warming, Covid vaccines, and the Moon landings.
The Tasmanian link
Some conspiracy theorists have been sharing a 2016 news report from the Australian TV network 7News – which has now been watched thousands of times.
In it, the newsreader reports on concerns by Tasmanian residents that the region’s worst floods in 40 years could have been linked to cloud seeding.
But a probe by the Tasmanian government found that cloud seeding did not contribute to or worsen the heavy rains – a conclusion since backed by independent scientists and experts.
“We don’t have a co-ordinated effort to change the weather, because it’s just physically and financially unfeasible,” says Dr Gilbert, who adds that even if cloud seeding played a role, it would have “an absolutely miniscule effect.”
There is no single cause for the intense rainfall Sydney has experienced in the last few days. But experts say the flooding has been worsened by climate change and a La Niña weather phenomenon.
HAS La Nina develops when strong winds blow the warm surface waters of the Pacific away from South America and towards Indonesia. In their place, colder waters come up to the surface.
In Australia, a La Niña increases the likelihood of rain, cyclones, and cooler daytime temperatures.
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